<template>
    <div class="music-list">
        <div class="back" @click="back">
            <i class="icon-back"></i>
        </div>
        <h1 class="title" v-html="title"></h1>
        <div class="bg-image" :style="bgstyle" ref="bgImage">
            <div class="play-wrapper">
                <div 
                class="play" 
                v-show="songs.length>0" 
                ref="playBtn"
                @click="randomPlayFunc"
                >
                    <i class="icon-play"></i>
                    <span class="text">随机播放全部</span>
                </div>
            </div>
            <div class="filter" ref="filter"></div>
        </div>
        <div class="bg-layer" ref="layer"></div>
        <scroll 
        :data="songs" 
        :probe-type="probeType"
        :listen-scroll="listenScroll" 
        class="list" 
        ref="list"
        @scroll="scrollFunc"
        >
            <div class="song-list-wrapper">
                <song-list 
                :songs="songs" 
                @select="selectItem"
                :rank="rank"
                >
                </song-list>
            </div>
            <div class="loading-container" v-show="!songs.length">
                <loading></loading>
            </div>
        </scroll>
    </div>
</template>

<script>
import Scroll from '../../base/scroll/scroll'
import Loading from '../../base/loading/loading'
import SongList from '../../base/song-list/song-list'
import {prefixStyle} from '../../common/js/dom.js'
import {mapActions} from 'vuex'

const RESOV_HEIGHT=40
const transform=prefixStyle('transform')
const backdrop=prefixStyle('backdrop-filter')

export default {
    data(){
        return {
            scrollY:0
        }
    },
    props:{
        bgImage:{
            type:String,
            default:''

        },
        songs:{
            type:Array,
            default:[]
        },
        title:{
            type:String,
            default:''
        },
        rank:{
            type:Boolean,
            default:false
        }
    },
    computed:{
        bgstyle(){
            return `background-image:url(${this.bgImage})`
        }
    },
    created(){
        this.probeType=3
        this.listenScroll=true
    },
    components:{
        Scroll,
        SongList,
        Loading
    },
    mounted(){
        this.imageHeight=this.$refs.bgImage.clientHeight
        this.minTranslateY=-this.imageHeight+RESOV_HEIGHT
        this.$refs.list.$el.style.top=`${this.imageHeight}px`
    },
    methods:{
        randomPlayFunc(){
            this.randomPlay({
                list:this.songs
            })
        },
        scrollFunc(pos){
            this.scrollY=pos.y
        },
        back(){
            this.$router.back()
        },
        selectItem(item,index){
            this.selectPlay({
                list:this.songs,
                index
            })
        },
        ...mapActions([
            'selectPlay',
            'randomPlay'
        ])
    },
    watch:{
        scrollY(newY){
            let translateY=Math.max(this.minTranslateY,newY)
            let zIndex=0
            let scale=1
            let blur=0
            this.$refs.layer.style[transform]=`translate3d(0,${translateY}px,0)`
            // this.$refs.layer.style['-webkit-transform']=`translate3d(0,${translateY}px,0)`
            const percent=Math.abs(newY/this.imageHeight)
            if(newY>0){
                scale=1+percent
                zIndex=10
            }else{
                blur=Math.min(20*percent,20)
            }
            this.$refs.filter.style[backdrop]=`blur(${blur}px)`
            // this.$refs.filter.style['-webkit-backgdrop-filter']=`blur(${blur}px)`
            if(newY<this.minTranslateY){
                zIndex=10
                this.$refs.bgImage.style.paddingTop=0
                this.$refs.bgImage.style.height=`${RESOV_HEIGHT}px`
                this.$refs.playBtn.style.display='none'
            }else{
                 this.$refs.bgImage.style.paddingTop='70%'
                this.$refs.bgImage.style.height=0
                this.$refs.playBtn.style.display=''
            }
            this.$refs.bgImage.style.zIndex=zIndex
             this.$refs.bgImage.style[transform]=`scale(${scale})`
            // this.$refs.bgImage.style['-webkit-transform']=`scale(${scale})`
        }
    }
}
</script>

<style lang='stylus' scoped>
@import "../../common/stylus/variable"
@import "../../common/stylus/mixin"
  .music-list
    position: fixed
    z-index: 100
    top: 0
    left: 0
    bottom: 0
    right: 0
    background: $color-background
    .back
      position absolute
      top: 0
      left: 6px
      z-index: 50
      .icon-back
        display: block
        padding: 10px
        font-size: $font-size-large-x
        color: $color-theme
    .title
      position: absolute
      top: 0
      left: 10%
      z-index: 40
      width: 80%
      no-wrap()
      text-align: center
      line-height: 40px
      font-size: $font-size-large
      color: $color-text
    .bg-image
      position: relative
      width: 100%
      height: 0
      padding-top: 70%
      transform-origin: top
      background-size: cover
      .play-wrapper
        position: absolute
        bottom: 20px
        z-index: 50
        width: 100%
        .play
          box-sizing: border-box
          width: 135px
          padding: 7px 0
          margin: 0 auto
          text-align: center
          border: 1px solid $color-theme
          color: $color-theme
          border-radius: 100px
          font-size: 0
          .icon-play
            display: inline-block
            vertical-align: middle
            margin-right: 6px
            font-size: $font-size-medium-x
          .text
            display: inline-block
            vertical-align: middle
            font-size: $font-size-small
      .filter
        position: absolute
        top: 0
        left: 0
        width: 100%
        height: 100%
        background: rgba(7, 17, 27, 0.4)
    .bg-layer
      position: relative
      height: 100%
      background: $color-background
    .list
      position: fixed
      top: 0
      bottom: 0
      width: 100%
      background: $color-background
      .song-list-wrapper
        padding: 20px 30px
      .loading-container
        position: absolute
        width: 100%
        top: 50%
        transform: translateY(-50%)
</style>
